[tracker] Fixes NB#196143, tracker-info core dumps with NULL cursor getting prefixes

[Martyn James Russell <mr src gnome org>]

commit 987e5f2e69bad841fd22730ef0ddc5c628d362fc
Author: Martyn Russell <martyn lanedo com>
Date:   Tue Oct 5 10:56:47 2010 +0100

    Fixes NB#196143, tracker-info core dumps with NULL cursor getting prefixes

 src/tracker-utils/tracker-info.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/src/tracker-utils/tracker-info.c b/src/tracker-utils/tracker-info.c
index 5c39724..f6efedb 100644
--- a/src/tracker-utils/tracker-info.c
+++ b/src/tracker-utils/tracker-info.c
@@ -126,6 +126,20 @@ get_prefixes (TrackerSparqlConnection *connection)
 
 	cursor = tracker_sparql_connection_query (connection, query, NULL, &error);
 
+	if (error) {
+		g_printerr ("%s, %s\n",
+			    _("Unable to retrieve namespace prefixes"),
+			    error->message);
+
+		g_error_free (error);
+		return retval;
+	}
+
+	if (!cursor) {
+		g_printerr ("%s\n", _("No namespace prefixes were returned"));
+		return retval;
+	}
+
 	while (tracker_sparql_cursor_next (cursor, NULL, NULL)) {
 		const gchar *key, *value;